Knowledge-Based Approach

• Typically our knowledge of a concept is not limited to the concept's features

• We usually have some knowledge of the relations among the features

• Casual relations

Ahn et al., (2000)

• Participants told members of a category tend to have three features

  • E.g., blurred vision; headaches, insomnia

• If one of the 'cause' was missing (blurred vision) in the description, then people did not rate the item as a member of the category

• The way we represent a concept changes depending on context (Barsalou, 2008)

  • If we hear the world frog in isolation, then the phrase "eaten by humans" probably remains inactive, however if you hear the word frog in a French restaurant then the phrase "eaten by humans" may well be activated by the word frog

• Yee and Thompson-Schill (2016) argue that there is no core representation activated across all possible contexts

Knowledge-Based Alternative

• Allows for several factors that other accounts couldn't explain as having an influence over categorisation

  • Casual relations

  • Context

  • Non-obvious or visible features

• Knowledge-based accounts also allow for ad hoc categories

Organisation of Concepts

• 3 levels of generality

  • Superordinate

    • Most general e.g., furniture

  • Basic

    • Intermediate level e.g., chair, lamp, table

  • Subordinate

    • Specific types of objects e.g., kitchen chair

Conceptual Hierarchies (Rosch et al., 1976)

• Ps listed attrivutes of concepts at 3 levels

  • Superordinate

    • Few attributes

    • Lacks informativeness

  • Basic

    • Many attributes

    • Maximal within-category similarity relative to between-category similarity

    • Balance of informativeness and economy

  • Subordinate

    • Many attributes, but similar for complementary categories informativeness good, but lacks economy

Special Properties of Basic Level Concept (Rosch et al., 1976)

• Objects are spontaneously named at this level

• Acquired first by children

• Similar overall shape

• Faster recognition compared to other levels

• We even tend to use similar motor movements for interacting with category members, for example we tend to physically behave in similar ways with chairs (all chairs) as opposed to tables

Hierarchies of Concepts - Limitations

• Not a single level of basic categories - familiarity matters!!!

  • Tanaka and Taylor (1991) examined the concepts of two groups of people - birdwatchers and dog experts. Showed images of dogs and birds

    • When dog experts were viewing bird pictures and birdwatchers view dog pictures, both groups used basic level names

    • When viewing from their expert domain - both groups used subordinate more often

• Perceptual distinctiveness

  • Typically as we have seen we work best at the basic level (dog vs cat) however, if the task involves perceptual distinctiveness then we see an advantage for superordinate categories (e.g., animal or vehicle)

• Hierarchical distinctiveness (large categories)

Collins & Loftus (1975) Semantic Networkjou8

• Shorter links to connect closely related concepts

• Longer links for less closely related subjects

• No hierarchical structure; based on person's experience

Assessing Semantic Relatedness

• Word association task - participants shown a word and asked to name the first word (or three words) that come to mind

• Feature overlay - extent to which different participants use same features to describe

• Distance ratings - Ss estimate distance between concepts

Spreading Activation

• Activation is the arousal level of a node

• Activity spreads out along any link that is connected to an activated node

• Concepts that receive activation are primed and more easily accessed from memory

Schemas

• Each other in order to create situation models of what happens around us

• Event indexing model argues propositions are link based on events being related by time, space, entity, causation and motivation – as parts of events are experiences they are represented overlapping on some of the dimensions (i.e. time or space).  Together the events = memory of the situation

• Schema – set of related propositions which forms a packet of typical knowledge about the world, events or people

• Schema - General knowledge or expectations, based on our relationship with a person, object or event

• Memory for common everyday events e.g., restaurant

• Schemas guide our recall

  • Consistency bias

    • Exaggerate the consistency between our feelings/beliefs

Schema-Based Approach

• Bartlett, 1932

• Memory uses world knowledge and schemata

• Schemata: frameworks for organising information in LTM

• At retrieval, Ps reconstruct memories base on their knowledge and schemata

• Bartlett rejected the idea of LTM as a warehouse where memory is stored, unchanged until retrieval

• Memory is an active and inaccurate process that encode information so as to 'make sure'

• Recall became more distorted with each re-telling

• People introduced material to make material more rational and coherent, more consistent with their assumptions and existing schema

• Memory of stories was reconstructed

• Forerunner of more recent work on memory distortions, eye witness memory etc.

Schemas and Incidental Learning

• Brewer & Treyans (1981)

• Do people show schema-driven memory errors?

• Participants asked to wait in 'office' which was a room containing a mixture of schema consistent objects (books, papers etc) and inconsistent objects

• Participants recalled more schema-consistent objects than scheme-inconsistent objects present

• However, they also falsely recalled more scheme-consistent objects than had actually been present

Why Do We Use Schemas?

• Allow us to form expectations

• Prevent cognitive overload

• Assist with missing information

• Assist in visual scene perception

Stereotypes

• Stereotypes

  • Schemas incorporating oversimplified generalisations (often negative) about certain groups

• We use them to reduce processing demands

• Not fixed - stereotypes (and schemas) can change across time

  • Garcia - Marques et al, (2006) asked participants to select 5 traits out of 43 that best represented various groups (e.g., immigrants) then again.2 weeks later = considerable instability!

• Influenced by context

Semantic Dementia

• Patterson et al. (2007) identify semantic dementia as a condition where there is widespread loss of knowledge about the meaning of concepts and words

• Different to Alzheimer's where the deficit is primarily with episodic memory

• Patients with semantic dementia have problems categorising objects from pictures, difficulty assigning detailed meaning to pictures and difficulty drawing objects

• In early stages autobiographical memory spared but by later stages impairment in these too